Semiconductor element having microcrystalline semiconductor material and manufacturing method thereof

ABSTRACT

In a semiconductor element comprising microcrystalline semiconductor, a semiconductor junction is provided within a microcrystal grain. Further, in a semiconductor element comprising microcrystalline semiconductor, providing microcrystal grains of different grain diameters as a mixture to form a semiconductor layer. Thereby, discontinuity of a semiconductor junction is improved to improve the characteristics, durability, and heat resisting properties of a semiconductor element. Distortion in a semiconductor layer is also reduced.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a semiconductor element and itsmanufacturing method, particularly to a functional semiconductor elementsuch as a photovoltaic element and a thin film transistor and itsmanufacturing method.

[0003] 2. Related Background Art

[0004] Microcrystalline silicon semiconductors have been presented in1979 (S. USUI and M. KIKUCHI, “PROPERTIES OF HEAVILY DOPED GD-Si WITHLOW RESISTIVITY”, Journal of Non-Crystalline Solids, 34 (1979), pp. 1 to11). This article has described that a low-resistivity microcrystallinesilicon semiconductor doped with phosphorous was able to be deposited bya glow discharge method.

[0005] The same fact is described in A. MATSUDA, S. YAMASAKI et al.,“Electrical and Structural Properties of Phosphorous-DopedGlow-Discharge Si:F:H and Si:H Films”, Japanese Journal of AppliedPhysics, Vol. 19, No. 6, JUNE, 1980, pp. L305 to L308.

[0006] Further, A. Matsuda, M. Matsumura et al., “Boron Doping ofHydrogenated Silicon Thin Films”, Japanese Journal of Applied Physics,Vol. 20, No. 3, MARCH, 1981, pp. L183 to L186 discusses thecharacteristics of a mixed-phase of boron-doped amorphous andmicrocrystalline silicon.

[0007] A. MATSUDA, T. YOSHIDA et al., “Structural Study onAmorphous-Microcrystalline Mixed-Phase Si:H Films”, Japanese Journal ofApplied Physics, Vol. 20, No. 6, JUNE, 1981, pp. L439 to L442 discussesthe structure of an amorphous and microcrystalline mixed-phase.

[0008] However, the possibility that such mixed layers of amorphous andmicrocrystalline silicon could be applied in semiconductor elements suchas solar cells has been suggested, but there has been no actualapplication.

[0009] Solar cells using microcrystalline silicon semiconductors havebeen described in U.S. Patent No. 4,600,801 “FLUORINATED P-DOPEDMICROCRYSTALLINE SILICON SEMICONDUCTOR ALLOY MATERIAL”, U.S. Patent No.4,609,771 “TANDEM JUNCTION SOLAR CELL DEVICES INCORPORATING IMPROVEDMICROCRYSTALLINE P-DOPED SEMICONDUCTOR ALLOY MATERIAL”, and U.S. Pat.No. 4,775,425 “P- AND N-TYPE MICROCRYSTALLINE SEMICONDUCTOR ALLOYMATERIAL INCLUDING BAND GAP WIDENING ELEMENTS, DEVICES UTILIZING SAME”.However, the microcrystalline silicon semiconductors described in thesepatents have been used in p-type or n-type semiconductor layers in solarcells of a pin structure using an amorphous i-type semiconductor layer.

[0010] Recently, articles on solar cells using microcrystalline siliconin an i-type semiconductor layer have been published. For example, thereis “ON THE WAY TOWARDS HIGH EFFICIENCY THIN FILM SILICON SOLAR CELLS BYTHE MICROMORPH CONCEPT”, J. Meier, P. Torres et al., Mat. Res. Soc.Symp. Proc., Vol. 420, (1996) p. 3. However, as acknowledged by theauthors of the article, the initial photoelectric conversion efficiencyin a single structure solar cell using microcrystalline silicon in ani-type semiconductor layer is 7.7%, which is lower than that for solarcells with the same structure using amorphous silicon.

[0011] The present inventors have diligently inspected the reason whythe conversion efficiency of solar cells using microcrystalline siliconsemiconductors in an i-type semiconductor layer is lower than that ofamorphous silicon solar cells with the same structure. The results makeclear that the main cause lies in the interfaces between the n-typesemiconductor layer or the p-type semiconductor layer with the i-typesemiconductor layer. Specifically, the present inventors have discoveredthat there are many defect states in the vicinity of the interface ofthe n-type semiconductor layer with the i-type semiconductor layer aswell as in the vicinity of the interface of the p-type semiconductorlayer with the i-type semiconductor layer, which function asrecombination centers. The existence of the recombination centersresults in reduction in number and lowering in transportability ofphoto-excited free carriers in the i-type semiconductor layer. As aresult, the open circuit voltage (Voc), short-circuit current (Jsc), andfill factor (FF) of the solar cell decline. Further, it is attributableto an increase in series resistance and a decline in the shuntresistance of the solar cell . As a result, the conversion efficiency ofthe solar cell declines.

[0012] When the inventors teamed up a transmission electron microscopewith a secondary ion mass spectrometer and searched for the cause of themany defect states in the vicinity of the interfaces mentiond above,they discovered that the n-type semiconductor layer and the i-typesemiconductor layer, or the p-type semiconductor layer and the i-typesemiconductor layer were discontinuously stacked. Thus, they assumedthat the reason why there were many defect states in the vicinity of theinterfaces mentioned above was that the n-type semiconductor layer andthe i-type semiconductor layer, or the p-type semiconductor layer andthe i-type semiconductor layer were discontinuously stacked.

[0013] Further, when usual semiconductor elements are left to stand inthe atmospheric environment, molecules in the air (water, oxygen,nitrogen, nitrogen oxides, sulfurous compounds, etc.) or the elementscontained therein may sometimes diffuse into the semiconductor elementto lower the characteristics of the semiconductor element. Similarly,when a semiconductor element such as a solar cell is encapsulated withanother material (encapsulant), a chemical substance (acetic acid, etc.)contained in the encapsulant may sometimes diffuse into thesemiconductor element to lower the characteristics of the semiconductorelement. In particular, when each layer is stacked discontinuously atthe semiconductor junction (junction of n-type semiconductor layer withi-type semiconductor layer, junction of p-type semiconductor layer withi-type semiconductor layer, etc.), the diffused substance will betrapped by the interface defects to lower the semiconductorcharacteristics.

[0014] When the inventors analyzed transmission electron microscope andX-ray diffraction data, it became clear that structural distortions wereliable to be concentrated in the relatively large spaces betweenmicrocrystal grains, where there were many defects. These defects willreduce the trans-portability (mobility) of photo-excited free carriersand shorten the life time thereof to lower the characteristics of thesemiconductor element.

[0015] The present invention aims to solve the above-mentioned problemsand improve the photoelectric conversion efficiency of a photoelectricconversion element represented by a solar cell.

[0016] The present invention also aims to eradicate the discontinuity inthe semiconductor junction portion to thereby provide a semiconductorelement with superior semiconductor characteristics.

[0017] The present invention further aims to reduce the defects betweenmicrocrystal grains and to dissolve the discontinuity at thesemiconductor junction portion to thereby provide a semiconductorelement with superior semiconductor characteristics.

[0018] In addition, the present invention aims to improve the heatresisting properties and durability of a semiconductor element.

SUMMARY OF THE INVENTION

[0019] A first aspect of the present invention is directed to asemiconductor element comprising microcrystalline semiconductor, havinga semiconductor junction in a microcrystal grain.

[0020] A second aspect of the present invention is directed to asemiconductor element comprising a semiconductor layer having firstelectric characteristics, a semiconductor layer having second electriccharacteristics, and a semiconductor layer having third electriccharacteristics stacked in the named order, wherein a microcrystal grainis present extending over at least a portion of the semiconductor layerhaving the first electric characteristics and at least a portion of thesemiconductor layer having the second electric characteristics.

[0021] A third aspect of the present invention is directed to a methodof manufacturing a semiconductor element, comprising the steps of:

[0022] forming a semiconductor layer having first electriccharacteristics on a substrate;

[0023] crystallizing the semiconductor layer having the first electriccharacteristics; and

[0024] growing a crystalline semiconductor layer having second electriccharacteristics on the crystallized semiconductor layer having the firstelectric characteristics, thereby growing a microcrystal grain so as toextend over the semiconductor layer having the first electriccharacteristics and the semiconductor layer having the second electriccharacteristics.

[0025] A fourth aspect of the present invention is directed to a methodof manufacturing a semiconductor element, comprising the steps of:

[0026] forming a crystalline semiconductor layer having first electriccharacteristics on a substrate; and

[0027] growing a crystalline semiconductor layer having second electriccharacteristics on the semiconductor layer having the first electriccharacteristics, thereby growing a microcrystal grain so as to extendover the semiconductor layer having the first electric characteristicsand the semiconductor layer having the second electric characteristics.

[0028] A fifth aspect of the present invention is directed to a methodof manufacturing a semiconductor element, comprising the steps of:

[0029] forming a semiconductor layer having first electriccharacteristics on a substrate;

[0030] growing a semiconductor layer having second electriccharacteristics on the semiconductor layer having the first electriccharacteristics; and

[0031] effecting annealing to form a microcrystal grain so as to extendover the semiconductor layer having the first electric characteristicsand the semiconductor layer having the second electric characteristics.

[0032] A sixth aspect of the present invention is directed to a methodof manufacturing a semiconductor element, comprising the steps of:

[0033] forming a crystalline semiconductor layer on a substrate; and

[0034] ion-implanting a dopant into the semiconductor layer to form asemiconductor junction in a microcrystal grain of the semiconductorlayer.

[0035] A seventh aspect of the present invention is directed to asemiconductor element comprising microcrystalline semiconductor, havinga region where microcrystal grains with different grain diameters arepresent as a mixture.

[0036] An eighth aspect of the present invention is directed to asemiconductor element comprising a semiconductor layer having firstelectric characteristics, a semiconductor layer having second electriccharacteristics and a semiconductor layer having third electriccharacteristics stacked in the named order, wherein microcrystal grainswith different grain diameters are present as a mixture in at least oneof the semiconductor layers.

[0037] An ninth aspect of the present invention is directed to a methodof manufacturing a semiconductor element, comprising the step ofgenerating a plasma in a gas phase to decompose a source gas thusforming a semiconductor layer comprising microcrystals on a substrate,wherein an electric power to be applied to the plasma is periodicallychanged to form a semiconductor layer comprising microcrystal grains ofdifferent sizes as a mixture.

[0038] A tenth aspect of the present invention is directed to a methodof manufacturing a semiconductor element, comprising the step ofgenerating a plasma in a gas phase to decompose a source gas thusforming a semiconductor layer comprising microcrystals on a substrate,wherein a halogen-containing gas is added at regular intervals into thesource gas to form a semiconductor layer comprising microcrystal grainsof different sizes as a mixture.

BRIEF DESCRIPTION OF THE DRAWINGS

[0039]FIG. 1 is a schematic sectional view showing an example of thelayer structure of a photovoltaic element, which is an example of thesemiconductor element of the present invention;

[0040]FIG. 2 is a schematic view showing an example of a deposited filmforming apparatus for producing a photovoltaic element, which is anexample of the semiconductor element of the present invention;

[0041]FIG. 3 is a schematic sectional view showing an example in which amicrocrystalline semiconductor layer is grown almost just above areflection increasing layer;

[0042]FIG. 4 is a schematic sectional view showing an example in whichan amorphous layer is deposited on a reflection increasing layer, and amicrocrystalline semiconductor layer is grown thereon;

[0043]FIG. 5 is a schematic sectional view showing an example in which amicrocrystalline semiconductor layer is deposited on a reflectionincreasing layer, and another microcrystalline semiconductor layer isgrown thereon; and

[0044]FIG. 6A is a schematic partial sectional view showing amicrocrystalline semiconductor layer in which the grain diameters ofmicrocrystal grains are uniform and FIG. 6B is a schematic partialsectional view showing a microcrystalline semiconductor layer in whichthe grain diameters of microcrystal grains are different.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] The present inventors have performed a rigorous investigation inorder to solve the above mentioned problems. As a result, it has beenfound that in a semiconductor element comprising microcrystallinesemiconductor, an effective way to solve such problems is providing asemiconductor junction within a microcrystal grain. In the semiconductorelement, at least a portion of each of two semiconductor layers withdifferent electric characteristics (for example a portion of the n-typesemiconductor layer and a portion of the i-type semiconductor layer or aportion of the p-type semiconductor layer and a portion of the i-typesemiconductor layer) a re formed in the vicinity of the interfacebetween the layers within the same microcrystal grain. In other words,in the semiconductor element, there are microcrystal grains that extendover two semiconductor layers. In this way, by forming a semiconductorjunction such as p/i or n/i within microcrystal grains, defect states inthe vicinity of the interface can be reduced to a great extent. As aresult, declines in the open circuit voltage (Voc), short circuitcurrent (Jsc), and fill factor (FF) of a solar cell are prevented.Further, increase in the series resistance and decrease in the shuntresistance of a solar cell can be prevented. As a result, the conversionefficiency of the solar cell can be improved.

[0046] Further, the heat resisting properties of the semiconductorelement can be improved by forming a semiconductor junction withinmicrocrystal grains.

[0047] In addition, discontinuity in layer interfaces in thesemiconductor junction portion can be eliminated and the characteristicsof the semiconductor element are improved by forming a semiconductorjunction within the microcrystal grains. For example, by forming asemiconductor junction within the microcrystal grains, a depletion layerof a semiconductor junction expands further than in conventionalsemiconductor elements having a semiconductor junction. As a result, therectifying characteristics are better than in a conventionalsemiconductor junction, and the dark current when applied with a reversebias can also be kept low.

[0048] The present inventors have discovered that in a semiconductorelement comprising microcrystalline semiconductors, providingmicrocrystal grains with different grain diameters as a mixture withinthe semiconductor layer and providing a semiconductor junction withinthe microcrystal grains are an effective way to solve theabove-mentioned problems. In the specification and claims, theexpression “a semiconductor layer comprising microcrystal grains ofdifferent grain diameters as a mixture” means a semiconductor layer inwhich microcrystal grains having different grain diameters without anyregularity are distributed almost at random. Further, the fact thatmicrocrystal grains with different grain diameters are present as amixture has been confirmed by calculating the average crystalline graindiameter from the half-width of the X-ray diffraction (220) peak andfinding the average crystalline grain diameter from the dark-field imageof a transmission electron microscope, and finding that they differed bymore than 50 Å. In the semiconductor element, by mixing microcrystalgrains with different crystal grain diameters, distortions can be madeeven smaller than when a three dimensional space (semiconductor layer)is filled with microcrystal grains of the same crystalline graindiameters. As a result, it is possible to increase the transportability(mobility) of photo-excited free carriers in the microcrystallinesemiconductor layer and to lengthen the life time the carriers. Further,in the semiconductor element, at least a portion of each of twosemiconductor layers with different electric characteristics (forexample, a portion of the n-type semiconductor layer and a portion ofthe i-type semiconductor layer or a portion of the p-type semiconductorlayer and a portion of the i-type semiconductor layer) are formed withinthe same microcrystal grains in the vicinity of the interface of the twolayers. In other words, in the semiconductor element, microcrystalgrains are present extending over two semiconductor layers. Forming asemiconductor junction such as p/i or n/i within microcrystal grains insuch a way can reduce the defect states in the vicinity of the interfaceto a great extent. As a result, declines in the open circuit voltage(Voc), short circuit current (Jsc), and fill factor (FF) of the solarcell are prevented. Further, increase in the series resistance anddecline in the shunt resistance of the solar cell are also prevented. Asa result, the conversion efficiency of the solar cell is improved.

[0049] Also in this case, the heat resisting properties of thesemiconductor element are also improved by forming a semiconductorjunction within the microcrystal grains.

[0050] Further, also in this case, discontinuity in the layer interfaceat the semiconductor junction is eliminated and the semiconductorelement characteristics are improved by forming a semiconductor junctionwithin microcrystal grains.

[0051] A photovoltaic element is taken as an example of thesemiconductor element of the present invention and is explainedreferring to the drawings hereinafter.

[0052]FIG. 1 shows an example of the layer structure of a photovoltaicelement, which is an example of the semiconductor element of the presentinvention. This photovoltaic element is composed of a substrate 111 (anelectroconductive substrate comprised of a metal such as stainless steelor an insulating substrate comprised of glass or the like), with areflection layer 110 comprised of a metal such as Al, Cu, or Ag, areflection increasing layer 109 comprised of a metallic oxide or thelike such as zinc oxide, indium oxide, or tin oxide, a bottomphotovoltaic element 112 comprising an n-type or p-type semiconductorlayer (the layer having the first electric characteristics) 108, ani-type semiconductor layer (the layer having the second electriccharacteristics) 107, and a p-type or n-type semiconductor layer (thelayer having the third electric characteristics) 106 and a topphotovoltaic element 113 comprising an n-type or p-type semiconductorlayer 105, an i-type semiconductor layer 104, and a p-type or n-typesemiconductor layer 103, and then a transparent electrode 102 such as ofITO and a grid (collector electrode) 101 on top. In this photovoltaicelement the bottom photovoltaic element i-type semiconductor layer isconstituted of microcrystalline silicon semiconductor.

[0053]FIGS. 3 through 5 show enlargements of the reflection increasinglayer 109, the layer 108 having the first electric characteristics andthe layer 107 having the second electric characteristics of FIG. 1.

[0054]FIG. 3 is an example in which microcrystalline semiconductorlayers 302 and 305 are grown almost just on a reflection increasinglayer 301. The semiconductor layer having the first electriccharacteristics is the portion 305 below the straight line 303. Thesemiconductor layer having the second electric characteristics is theportion 302 above the straight line 303. FIG. 4 is an example in whichan amorphous semiconductor layer is deposited on the reflectionincreasing layer 401 in several 100 Å for example, and microcrystallinesemiconductor layers 402 and 405 are grown thereon. The semiconductorlayer having the first electric characteristics is the portion 405 belowthe straight line 403. The semiconductor layer having the secondelectric characteristics is the portion 402 above the straight line 403.FIG. 5 is an example in which a microcrystalline semiconductor layer 504is deposited on the reflection increasing layer 501 in several 100 Å forexample, and microcrystalline semiconductor layers 502 and 505 are grownthereon. The semiconductor layer having the first electriccharacteristics 505 is the portion below the straight line 503. Thesemiconductor layer having the second electric characteristics 502 isthe portion above the straight line 503. In either example, asemiconductor junction is present within the microcrystal grains. Theshape of the microcrystals having a semiconductor junction within themicrocrystal grains is preferably a columnar shape when observed with atransmission electron microscope. One example of the preferredembodiments of the content of an additive for changing the electriccharacteristics of microcrystals having a semiconductor junction withinmicrocrystal grains is such that the content is varied in the directionof thickness of the semiconductor layer having the first electriccharacteristics.

[0055]FIG. 6A is a schematic partial sectional view showing amicrocrystalline semiconductor layer in which the grain diameters ofmicrocrystal grains are uniform and FIG. 6B is a schematic partialsectional view showing a microcrystalline semiconductor layer in whichthe grain diameters of microcrystal grains are different. In themicrocrystalline semiconductor layer of FIG. 6A, since the graindiameters of the microcrystal grains 601 are uniform, an amorphous layerwith many defects unfilled by microcrystal grains are present in themicrocrystalline semiconductor layer. In FIG. 6A reference numeral 602designates a space not filled with microcrystals. On the other hand,since the microcrystalline semiconductor layer of FIG. 6B is constitutedof microcrystal grains with different grain diameters, there issubstantially no space unfilled with microcrystal grains. As a result,the mobility and life time of carriers of the microcrystallinesemiconductor layer of FIG. 6B will be greater than those of FIG. 6A.

[0056]FIG. 2 is an example of a deposited film forming apparatus forproducing a photovoltaic element, which is an example of thesemiconductor element of the present invention. This deposited filmforming apparatus is constructed of a load chamber 201, amicrocrystalline silicon i-type semiconductor layer deposition chamber202, a silicon semiconductor layer (i-type semiconductor layer, p-typesemiconductor layer, n-type semiconductor layer) deposition RF chamber203, a microcrystalline silicon germanium i-type semiconductor layerdeposition chamber 204, and an unloading chamber 205. The loadingchamber is equipped with a laser-annealing heater not shown in thedrawing, and a window 222 for irradiating the semiconductor layer with alaser which is not shown in the drawing.

[0057] Gate valves 206, 207, 208, and 209 separate each chamber so thatthe source gases do not mix. The microcrystalline silicon i-typesemiconductor layer deposition chamber 202 is constructed of a heater211 for substrate heating and a plasma CVD chamber 210. The RF chamber203 is equipped with a heater 212 for n-type semiconductor layerdeposition and a deposition chamber 215 for depositing the n-typesemiconductor layer, a heater 213 for depositing the i-typesemiconductor layer and a deposition chamber 216 for depositing thei-type semiconductor layer, and a heater 214 for depositing the p-typesemiconductor layer and a deposition chamber 217 for depositing thep-type semiconductor layer. The microcrystalline silicon germaniumi-type semiconductor layer deposition chamber 204 has a heater 218 and aplasma CVD chamber 219. A substrate is attached to a substrate holder221, which is moved by a roller driven from the outside above a rail220. For depositing the microcrystalline semiconductor, microwave plasmaCVD method or VHF plasma CVD method are preferably used, but RF plasmaCVD method can also be used.

[0058] A photovoltaic element which is an example of the semiconductorelement of the present invention, is formed as described below.

[0059] First, an SUS substrate 111 having a reflective layer 110 and areflection increasing layer 109 formed thereon is set on the substrateholder 221, and then set on the rail 220 inside the loading chamber 201.The loading chamber 201 is exhausted to a vacuum degree under of severalmTorr (1 Torr=133 Pa) or less. The gate valves 206 and 207 are opened,and the substrate holder is transferred to the n-type semiconductorlayer deposition chamber 215 of the chamber 203. Each gate valve isclosed and the n-type semiconductor layer 108 is deposited with desiredsource gases in a desired layer thickness. After exhaustingsufficiently, the substrate holder is transferred to the loading chamber201. The substrate is heated with a heater not shown in the drawinguntil the substrate temperature reaches 400° C., and after the substratetemperature has become constant, the n-type semiconductor layer 108 iscrystallized with an XeCl laser not shown in the drawing. The internalpressure of the loading chamber during the laser irradiation ismaintained at a degree of vacuum not higher than 10⁻³ Torr. Thesubstrate holder is transferred to the microcrystalline silicon i-typesemiconductor layer deposition chamber 202 and the gate valves 206 and207 are closed. The substrate is heated with the heater 211 to a desiredsubstrate temperature; a necessary amount of desired source gases areintroduced; a desired degree of vacuum is attained; predeterminedmicrowave energy or VHF energy is introduced into the deposition chamber210; and a plasma is generated to deposit the microcrystalline siliconi-type semiconductor layer 107 in a desired layer thickness on then-type semiconductor layer 108. At this time, in order that the i-typesemiconductor layer 107 is epitaxially grown on the n-type semiconductorlayer 108, it is preferred that the i-type semiconductor layer 107 isdeposited continuously after hydrogen plasma treatment of the n-typesemiconductor layer 108 or that the substrate temperature duringdeposition of the i-type semiconductor layer 107 is made higher than thesubstrate temperature during deposition of the n-type semiconductorlayer 108.

[0060] Next, the chamber 202 is exhausted sufficiently; the gate valve207 is opened; and the substrate holder 221 is transferred from thechamber 202 to the chamber 203. The substrate holder 221 is transferredto the p-type semiconductor layer deposition chamber 217 of the chamber203, and the substrate is heated to a desired temperature with theheater 214. The deposition chamber 217 is supplied with source gases forp-type semiconductor layer deposition at a desired flow rate, and an RFenergy is introduced into the deposition chamber 217 while maintaining adesired degree of vacuum in the deposition chamber 217. Then the p-typesemiconductor layer 106 is deposited in a desired layer thickness. Afterdepositing the p-type semiconductor layer 106, the deposition chamber217 is exhausted sufficiently, and the substrate holder 227 istransferred to the n-type semiconductor layer deposition chamber 215within the same chamber 203. An n-type semiconductor layer 105 isdeposited on the p-type semiconductor layer 106 in the same way as then-type semiconductor layer 108 mentioned previously. The depositionchamber 215 is exhausted sufficiently, and the substrate holder 221 istransferred to the i-type semiconductor layer deposition chamber 216.The substrate is heated to a desired temperature with the heater 213.The deposition chamber 216 is supplied with source gases for i-typesemiconductor layer deposition at a desired flow rate, and a desired RFenergy is introduced while maintaining a desired pressure in thedeposition chamber 216. Thereby the i-type semiconductor layer 104 isdeposited in a desired film thickness on the n-type semiconductor layer105. Next, the deposition chamber 216 is exhausted sufficiently; thesubstrate holder 221 is transferred from the deposition chamber 216 tothe deposition chamber 217; and a p-type semiconductor layer 103 isdeposited on the i-type semiconductor layer 104 in the same way as thep-type semiconductor layer 106 mentioned previously. After exhaustingthe deposition chamber 217 sufficiently in the same manner as mentionedpreviously, the gate valves 208 and 209 are opened, and the substrateholder 221 having set thereon the substrate with deposited semiconductorlayers is transferred to the unloading chamber 205. All of the gatevalves are closed, nitrogen gas is introduced into the unloading chamber205; and the substrate is cooled to a desired temperature. Afterwards,the taking out valve of the unloading chamber 205 is opened to take outthe substrate holder 221. Using a vaporizer for transparent electrodedeposition (not shown), a transparent electrode 102 is deposited on thep-type semiconductor layer 103 in a desired layer thickness. Then, usingthe vaporizer (not shown) in the same way, a collector electrode 101 isdeposited on the transparent electrode 102.

[0061] Incidentally, when the microcrystalline i-type semiconductorlayer 107 is formed by use of silicon germanium instead of silicon, thechamber 204 may be used instead of the chamber 202.

[0062] Further, a semiconductor element having a semiconductor junctionwithin microcrystal grains may also be formed in the following ways.

[0063] (1) A crystalline semiconductor layer having first electriccharacteristics (a doped semiconductor layer), and then amicrocrystalline semiconductor layer having second electriccharacteristics (a non-doped microcrystalline semiconductor layer or amicrocrystalline semiconductor layer having a different electriccharacteristics from the first doped semiconductor layer) is depositedby changing the source gases under conditions such that microcrystalsgrow continuously, thus forming a semiconductor junction within themicrocrystal grains.

[0064] (2) A crystalline semiconductor layer having first electriccharacteristics is formed; a microcrystalline or amorphous semiconductorlayer having second electric characteristics on the semiconductor layer;and the both semiconductor layers are annealed at a temperature belowthe melting points, thus forming a semiconductor junction within themicrocrystal grains.

[0065] (3) A microcrystalline semiconductor layer having first electriccharacteristics is formed; hydrogen plasma treatment is applied onto thesemiconductor layer to clean the surface of the microcrystallinesemiconductor layer having the first electric characteristics; and thena microcrystalline semiconductor layer having second electriccharacteristics is epitaxially grown on the microcrystallinesemiconductor layer having the first electric characteristics to form asemiconductor junction within the microcrystal grains.

[0066] (4) An amorphous or crystalline semiconductor layer having firstelectric characteristics is formed; an amorphous or microcrystallinesemiconductor layer having second electric characteristics is depositedon the semiconductor layer; and then recrystallization with an excimerlaser (laser annealing) is carried out to form a semiconductor junctionwithin the microcrystal grains.

[0067] As the energy density of laser in recrystallization with anexcimer laser, 200 mJ/cm² to 800 mJ/cm² is preferred. The total layerthickness of the first and the second semiconductor layers wheneffecting the laser annealing is preferably 100 Å to 700 Å. Afterrecrystallization, epitaxially growing on the semiconductor layer withthe second electric characteristics a semiconductor layer with the sameelectric characteristics makes it possible to increase the layerthickness of the semiconductor layer having the second electriccharacteristics. When performing the laser annealing, it is preferableto increase the environment temperature, specifically to 100-800° C.Particularly, when a supporting member (substrate) with low heatresistance properties such as stainless thin film or glass is used, theenvironment temperature is preferably 100-600° C. Such lasers as ArF(wavelength: 193 nm), KrF (wavelength: 248 nm), XeCl (wavelength: 308nm), or XeF (wavelength: 351 nm) are included as suitable ones for laserannealing. When annealing a silicon type semiconductor layer, XeCl(wavelength: 308 nm) is particularly preferable.

[0068] (5) A crystalline semiconductor with first electriccharacteristics is formed and ion implanting an impurity (a dopant) inthe semiconductor enables formation of a semiconductor junction withinthe same semiconductor.

[0069] In this case, it is preferred that after ion implantation,thermal annealing is carried out within a range of 100 to 800° C.

[0070] The present invention can be applied to formation of not onlysemiconductor junctions where one layer is not doped such as p/i or n/ijunction, but also semiconductor junctions where the layers haveopposite electric characteristics such as n/p junction, or semiconductorjunctions where the layers have the same electric characteristics suchas n/n or p/p but are different in dopant concentration from each other.

[0071] The microcrystalline semiconductor layer comprised ofmicrocrystal grains with different grain diameters can be formed in thefollowing ways, for example.

[0072] (1) During the process of depositing a microcrystallinesemiconductor layer while diluting a source gas with a large amount ofhydrogen, the power applied to the plasma is periodically changed.

[0073] By doing so, at portions of the growing surface of thesemiconductor layer where crystals will grow with difficulty, thecrystal growth is promoted by the active hydrogen. As a result, thesemiconductor layer is filled with microcrystal grains having differentgrain diameters.

[0074] The applied power is preferably changed with 1.1 to 2 times thevalue before the change being the maximum value. If it is changed by afactor over 2 times, there is a possibility that the influence on thegrowing surface of the semiconductor may be so large as to increasedefect states.

[0075] (2) A microcrystalline semiconductor layer is deposited whileadding a halogen-containing gas to the source gases at regularintervals.

[0076] By doing so, it is possible to activate the growing surface ofthe semiconductor layer where crystal growth is difficult to promote thecrystal growth. As a result, the semiconductor layer is filled withmicrocrystal grains of different crystal diameters.

[0077] When adding the halogen-containing gas, it is preferable to addit at a ratio (volume concentration) of 0.2 to 0.9 times the source gasnot containing a halogen. If the addition amount of thehalogen-containing gas exceeds this range, the plasma will be unstableand there is a possibility that a desired semiconductor film may not beobtained.

[0078] The semiconductor layers adjacent to the semiconductor junctionwithin the microcrystal grains (a semiconductor layer having firstelectric characteristics and a semiconductor layer having secondelectric characteristics) can be either amorphous or crystalline duringdeposition if crystallization is carried out by a post-treatment. If nocrystallization by a post-treatment is carried out, they need to becrystalline during deposition. When they are made crystalline duringdeposition, they are preferably microcrystalline semiconductors.

[0079] The average crystal grain diameter of the microcrystal grains arepreferably 100 Å to 1000 Å when obtained by calculation using theScherrer's equation from the half-width of the X-ray diffraction (220)peak. If the average diameter is determined from the dark field image ofa transmission electron microscope, it is preferably within 100 Å to 10μm. When the average crystal grain diameter of columnar microcrystalsusing a transmission electron microscope, it is preferred that ageometric mean of the long axis and the short axis thereof is within theabove range.

[0080] Further, the preferred proportion of amorphous phase contained inthe microcrystalline semiconductor is such that when observed with theRaman spectrum, the ratio of amorphous phase related peaks to crystalphase related peaks is not more than 70%. If the average crystallinegrain diameter is less than 100 Å, more amorphous will exist on thecrystal grain boundaries and photodeterioration is liable to beoccurred. Also, if the crystal grain diameter is too small, there is apossibility that the mobility and life time of electrons and positiveholes may be smaller to lower the characteristics as semiconductor. Onthe other hand, if the average crystal grain diameter calculated usingthe Scherrer's equation is greater than 1000 Å, there is a possibilitythat relaxation of the crystal grain boundaries may not progresssufficiently, defects such as dangling bonds may arise in the crystalgrain boundaries, and the defects may act as recombination centers forelectrons or positive holes, whereby the characteristics of themicrocrystalline semiconductor may be lowered. As the shape ofmicrocrystals, a shape which is long and thin (columnar) in thedirection of movement of the charge is preferred. In addition, theproportion of hydrogen atoms or halogen atoms contained in themicrocrystalline semiconductor layer of the present invention ispreferably not more than 30%.

[0081] The semiconductor layers used in the semiconductor element of thepresent invention include a doped layer such as a p-type semiconductorlayer or n-type semiconductor layer, an i-type semiconductor layer, orthe like.

[0082] When the present invention is applied to a photovoltaic element,the doped layer is an important layer that influences thecharacteristics of the element, and the i-type semiconductor layer isalso another important layer for carrier generation and transportationby light incidence.

[0083] As the amorphous semiconductor materials, microcrystallinesemiconductor materials and polycrystalline semiconductor materials thatcan preferably be applied to the semiconductor element of the presentinvention, there are included, for example, a-Si:H, a-Si:HX, a-SiC:H,a-SiC:HX, a-SIGe:H, a-SiGeC:H, a-SiO:H, a-SiN:H, a-SiON:HX, a-SiOCN:HX,μc-Si:H, μc-SiC:H, μc-Si:HX, μc-SiC:HX, μc-SiGe:H, μc-SiO:H, μc-SiGeC:H,μc-SiN:H, μc-SiON:HX, μc-SiOCN:HX, poly-Si:H, poly-Si:HX, poly-SiC:H,poly-SIC:HX, poly-SiGe:H, poly-Si, Poly-SiC, and poly-SiGe can be usedfavorable.

[0084] When these materials are applied to doped layers, it ispreferable to add a p-type valency controller (Group III atoms ofPeriodic Table: B, Al, Ga, In, or Tl) or an n-type valency controller(Group V atoms of Periodic Table: P, As, Sb, or Bi) at a highconcentration. The contents of Group III atoms in the p-typesemiconductor layer and Group V atoms in the n-type semiconductor layeris preferably 0.1 to 50 atomic Further, the hydrogen atoms (H, D) and/orthe halogen atoms (F, Cl, etc.) contained in the p-type semiconductorlayer or the n-type semiconductor layer have a function of compensatingfor the dangling bonds of the p-type or the n-type semiconductor layer,thus improving the doping efficiency of the p-type or n-typesemiconductor layer. The content of the hydrogen atoms and/or halogenatoms in the p-type or n-type semiconductor layer is preferably 0.1 to40 atomic %. In particular, when the p-type or n-type semiconductorlayer is crystalline, the content of hydrogen atoms and/or halogen atomsis preferably 0.1 to 8 atomic %.

[0085] Further, for the semiconductor layers of the semiconductorelement of the present invention, it is preferred that the content ofthe hydrogen atoms (H, D) and/or the halogen atoms (F, Cl, etc.) islarger in the vicinity of each of the interfaces of p-type semiconductorlayer/i-type semiconductor layer or n-type semiconductor layer/i-typesemiconductor layer. Preferably, the content of the hydrogen atomsand/or halogen atoms in the vicinity of the interfaces is preferablywithin a range of 1.1 to 2 times the content of the bulk area in thecase of the p-type semiconductor layer or the n-type semiconductorlayer, and is preferably within a range of 1.1 to 2 times the content ofthe bulk area in the case of the i-type semiconductor layer. Such largercontents of hydrogen atoms or halogen atoms in the vicinity of theinterfaces (p-type semiconductor layer/i-type semiconductor layer,n-type semiconductor layer/i-type semiconductor layer) can reduce defectstates and mechanical distortions in the vicinity of the interfaces,thereby improving the characteristics of the semiconductor element ofthe present invention.

[0086] When a multiple-element (alloy) semiconductor layer such as SiC,SiGe, etc., it is preferable that the content of hydrogen atoms and/orhalogen atoms is changed in response to the change in content of siliconatoms. In the semiconductor layer, depending on the bandgap, the contentof hydrogen atoms and/or halogen atoms is smaller at a portion of narrowbandgap. Incidentally, it is preferred that the content of the hydrogenatoms and/or halogen atoms at a portion where the content of siliconatoms is the minimum is 1 to 10 atomic %, and is 0.3 to 0.8 times thecontent at a portion where the content of hydrogen atoms and/or halogenatoms is the maximum.

[0087] Although the details of the mechanism are not clear, it isconsidered that when a alloy semiconductor containing silicon atoms andgermanium atoms is deposited, a difference arises in the electromagneticwave energies acquired by each of the atoms due to the differences inionization rates of the silicon atoms and germanium atoms, with theresult that even if the content of the hydrogen and/or halogen in thealloy semiconductor is small, the relaxation proceeds sufficiently toprovide a high quality alloy semiconductor.

[0088] The preferred electric characteristics for the p-typesemiconductor layer and the n-type semiconductor layer when applying thesemiconductor element of the present invention to a photovoltaic elementis such that the activation energy is not more than 0.2 eV, optimallynot more than 0.1 eV. The resistivity is preferably not more than 100Ωcm, optimally not more than 1 Ωcm. The layer thickness of the p-typesemiconductor layer and the n-type semiconductor layer is preferably 1to 50 nm, optimally 3 to 10 nm.

[0089] As the p-type semiconductor layer or the n-type semiconductorlayer on the light incidence side, a crystalline semiconductor layerwith less absorption of light or an amorphous semiconductor layer with alarge bandgap is suitable.

[0090] As the i-type semiconductor layer in the semiconductor element ofthe present invention, a semiconductor layer that is slightly of thep-type or n-type (i.e., substantially i-type semiconductor layer) can beused (whether it becomes the p-type or n-type depends on thedistribution of characteristic defects such as tail state).

[0091] As the i-type semiconductor layer when the semiconductor elementof the present invention is applied to a photovoltaic element, there cansuitably be used, in addition to semiconductors with a uniform bandgap,those semiconductor which contain silicon atoms and germanium atoms suchthat the bandgap changes smoothly in the direction of layer thickness ofthe i-type semiconductor layer, and that the minimum of the bandgap isoffset from the central position of the i-type semiconductor layertoward the interface between the p-type semiconductor layer and thei-type semiconductor layer. Further, a semiconductor layer doped withboth a valency controller to be a donor and a valency controller to bean acceptor is also suitable as the i-type semiconductor layer.

[0092] Further, it is preferred that the bandgap of the i-typesemiconductor layer is so designed that it becomes greater toward eachof the interfaces of p-type semiconductor layer/i-type semiconductorlayer and n-type semiconductor/i-type semiconductor layer. Such designmakes it possible to increase the photovoltage and photocurrent of thephotovoltaic element and to prevent photodeterioration in long-term use,or the like.

[0093] The preferred layer thickness of the i-type semiconductor layerin the case of a photovoltaic element depends largely on the structureof the element (for example single cell, tandem cell, or triple cell)and on the bandgap of the i-type semiconductor layer, but 0.7 to 30.0 μmis a suitable thickness.

[0094] Next, as the preferred methods for deposition of semiconductorlayers of the semiconductor element of the present invention, there areincluded RF plasma CVD, VHF plasma CVD, and microwave plasma CVD. Thepreferred range for the frequency of RF and VHF is 1 MHz to 300 MHz. ForRF, a frequency in the vicinity of 13.56 MHz is optimal, and for VHF afrequency in the vicinity of 105 MHz is optimal. For the microwave, 0.5GHz to 10 GHz is a preferred frequency range.

[0095] In particular, when depositing microcrystalline silicon, sincethe deposition rate depends on the electromagnetic wave used and becomeslarger with increasing frequency in a given input energy, using highfrequency electromagnetic waves is suitable.

[0096] As the source gases suitable for deposition of the semiconductorlayers of the semiconductor element of the present invention, there canbe included a gas comprised of a gasifiable compound containing siliconatoms, a gas comprised of a gasifiable compound containing germaniumatoms, a gas comprised of a gasifiable compound containing carbon atoms,or a mixture gas thereof.

[0097] As the compounds which contains silicon atoms and are gasifiable,there are included, for example, SiH₄, Si₂H₆, Si₃H₈, SiF₄, SiHF₃,SiH₂F₂, SiH₃F, SiH₃Cl, SiH₂Cl₂, SiHC1₃, SiCl₄, SiD₄, SiHD₃, SiH₂D₂,SiH₃D, SiD₃F, SiD₂F₂, SiHD₃, Si₂H₃D₂, etc.

[0098] As the compounds which contains germanium atoms and aregasifiable, there are included, for example, germanium compounds such asGeH₄, GeF₄, GeHF₃, GeH₂F₂, GeH₃F, GeHCl₃, GeH₂Cl₂, GeH₃Cl, GeHD₃,GeH₂D₂, GeH₃D, GeD₄, Ge₂H₆, Ge₂D₆, etc.

[0099] As the compounds which contains carbon atoms and are gasifiable,there are included, for example, compounds represented by C_(n)H_(2n+2)(n is an integer) such as CH₄, etc., compounds represented byC_(n)H_(2n) (n is an integer) such as C₂H₂, etc., and CD₄, C₆H₆, CO₂,CO, or the like.

[0100] Further, the source gases may contain a gas that containsnitrogen atoms or a gas that contains oxygen atoms.

[0101] The gases containing nitrogen atoms include N₂, NH₃, ND₃, NO,NO₂, N₂O, etc.

[0102] The gases containing oxygen atoms include gases as O₂, CO, CO₂,NO, NO₂, N₂O, CH₃CH₂OH, CH₃OH, etc.

[0103] Further, the above gasifiable compounds may be suitably dilutedwith such gases as H₂, He, Ne, Ar, Xe, or Kr to be introduced into thedeposition chamber.

[0104] In particular, when depositing a microcrystalline semiconductorlayer of the present invention, it is preferred that these source gasesare diluted with hydrogen gas or helium gas in order to form a goodmicrocrystalline semiconductor. The dilution rate with hydrogen gas ispreferably 10 or more fold. The especially preferred range of dilutionrate is from 10 to 100 fold. If the dilution rate is too small,formation of microcrystals becomes difficult and amorphous phase isliable to be formed. On the other hand, if the dilution rate is toolarge, the microcrystal deposition rate is too small and problems inpractical use arise.

[0105] In particular, when depositing microcrystalline semiconductor ora semiconductor layer with less light absorption or with a large bandgapsuch as a-SiC:H or the like, it is preferable to dilute the source gas 2to 100 fold with hydrogen gas, etc. and to make the input RF power, VHFpower, or microwave power relatively high.

[0106] When depositing a p-type semiconductor layer or an n-typesemiconductor layer, it is preferable to add a compound that contains avalency controller (Group III or Group V atoms of Periodic Table) to thesource gases in order to effect valency control.

[0107] As the compounds for introducing Group III atoms, there caneffectively be used boron hydrides such as B₂H₆, B₄H₁₀, B₅H₉, B₅H₁₁,B₆H₁₀, B₆H₁₂, B₆H₁₄, etc. or boron halides such as BF₃, BCl₃, etc. forboron atom introduction. In addition, such compounds as AlCl₃, GaCl₃,InCl₃, or TlCl₃ can be included as compounds for introducing Group IIIatoms other than boron. Of these compounds B₂H₆ and BF₃ are especiallysuitable.

[0108] As the compounds for introducing Group V atoms, there caneffectively be used phosphorous hydrides such as PH₃, P₂H₄, etc. andphosphorous halides such as PH₄I, PF₃, PF₅, PCl₃, PCl₅, PBr₃, PBr₅, PI₃,etc. for phosphorous atom introduction. In addition, such compounds asAsH₃, AsF₃, AsCl₃, AsBr₃, AsF₅, SbH₃, SbF₃, SbF₅, SbCl₃, SbCl₅, BiH₃,BiCl₃, and BiBr₃ can be included as compounds for introducing Group Vatoms other than phosphorous. Of these compounds PH₃ and PF₃ areespecially suitable.

[0109] When depositing a semiconductor layer with the RF plasma CVDmethod mentioned previously, the preferred deposition conditions aresuch that the substrate temperature in the deposition chamber is 100 to350° C.; the internal pressure is 0.1 to 10 Torr, the RF power is 0.01to 5.0 W/cm², and the deposition rate is 0.1 to 30 Å/sec. Further, whendepositing a semiconductor layer with the RF plasma CVD method, thecapacitive coupled RF plasma CVD method is suitably used.

[0110] When depositing a semiconductor layer with the microwave plasmaCVD method, the preferred deposition conditions are such that thesubstrate temperature in the deposition chamber is 100 to 400° C., theinternal pressure is 0.5 to 30 mTorr, and the microwave power is 0.01 to1.0 W/cm³. As the microwave plasma CVD apparatus used when depositing asemiconductor layer by microwave plasma CVD method, a method is suitablein which the microwaves are introduced by a waveguide through adielectric window (such as of aluminum ceramics) into the depositionchamber.

[0111] The substrate temperature for depositing a microcrystallinesemiconductor layer suited to the present invention is 100 to 500° C. Itis desirable that when increasing the deposition rate is desired, thesubstrate is kept at a relatively high temperature. As a suitable rangefor degree of vacuum in the chamber during deposition of themicrocrystalline semiconductor layer of the present invention, the rangeof 1 mTorr-1 Torr is included. Especially when depositing themicrocrystalline semiconductor layer by the microwave plasma CVD method,1 mTorr-10 mTorr is preferable as the degree of vacuum.

[0112] As a suitable range for input power for the chamber whendepositing the microcrystalline semiconductor layer of the presentinvention, 0.01-10 W/cm³ is included. When it is defined by therelationship of source gas flow rate and input power, the power limitedregion is suitable in which the deposition rate depends on the inputpower.

[0113] Further, the distance between the substrate and the electrodesfor power input is an important factor in the deposition of themicrocrystalline semiconductor layer of the present invention. In orderto obtain a microcrystalline layer suited to the present invention it ispreferred to set the distance to be 10 mm-50 mm.

[0114] The i-type semiconductor layer containing silicon atoms orgermanium atoms formed by the above described deposited film formationmethod is such that there are less tail states on the valence band sideeven when the deposition rate is over 5 nm/sec, and that the tail stateshave an inclination of not more than 60 meV, and that the density ofdangling bonds determined by the electron spin resonance (esr) is notmore than 10¹⁷/cm³.

[0115] The present invention is explained in detail below based onExamples. Of course, it is to be understood that the present inventionis not limited to the following examples.

EXAMPLE 1

[0116] In this example a photovoltaic element was produced using thedeposited film forming apparatus shown in FIG. 2. The depositionconditions of each of the semiconductor layers are shown in Table 1. Theformation of the members such as electrodes in all the examplesincluding this example and comparative examples was made following aconventional method. The microcrystalline semiconductor having asemiconductor junction within the same microcrystalline semiconductor ofthe present invention was used between the n-type semiconductor layer n1and an i-type semiconductor layer i1 of the bottom photovoltaic element.After deposition of the n-type semiconductor layer n1, the n-typesemiconductor layer n1 was irradiated with an excimer laser under theconditions shown in Table 2 in the loading chamber to crystalize then-type semiconductor layer n1. Afterwards, the i-type semiconductorlayer i1 was successively deposited on the n-type semiconductor layer nlby the VHF plasma CVD method.

COMPARATIVE EXAMPLE 1

[0117] A photovoltaic element for comparison with Example 1 was producedin a similar manner to that of Example 1 with the exception that then-type semiconductor layer n1 was not treated with an excimer laser.

COMPARISON OF EXAMPLE 1 WITH COMPARATIVE EXAMPLE 1

[0118] The characteristics of the photovoltaic element thus formed weremeasured and evaluated using WXS-130S-20T (trade name; mfd. by WACOMCO.) as a light source. The spectrum of the light source was AM 1.5 andthe light intensity was 1 sun. The results are shown in Table 3 in termsof relative values when the results of Comparative Example 1 areexpressed as 1. The photovoltaic element of Example 1 comprisingmicrocrystalline semiconductor with a semiconductor junction within thesame microcrystalline semiconductor of the present invention showedexcellent photovoltaic characteristics compared to the ComparativeExample 1 element. Further, as compared with the Comparative Example 1element, the photovoltaic element of Example 1 had a lower seriesresistance and a larger shunt resistance.

[0119] Then, 100 photovoltaic elements each were produced under the sameconditions as Example 1 and Comparative Example 1. These photovoltaicelements were allowed to stand for 2000 hours in an atmospherecontaining acetic acid at 85° C. temperature and 85% humidity.Afterwards, the photovoltaic characteristics were measured. Compared tothe elements of Comparative Example 1, the characteristics of the 100photovoltaic elements of Example 1 showed an extremely small variance.In other words, the photovoltaic elements of the present invention hadan extremely high resistance to environment (durability).

[0120] When a cross section of each of these photovoltaic elements wasobserved with a transmission electron microscope, it was confirmed forthe photovoltaic elements of Example 1 that the region thought to be theboundary between the n-type semiconductor layer and the i-typesemiconductor layer was constituted of microcrystal grains with a lengthin the layer thickness direction of 2000-4000 Å. Further, it wasconfirmed through secondary ion mass spectroscopy that the impurities(dopant) were localized on the substrate side of the microcrystalgrains.

EXAMPLE 2

[0121] A photovoltaic element was produced under the deposited filmformation conditions shown in Table 4 using the deposited film formingapparatus of FIG. 2 in the same manner as in Example 1. The n-typesemiconductor layer n1 was irradiated with an excimer laser under theconditions shown in Table 5 to crystallize it in a similar manner tothat of Example 1. A bottom i-type semiconductor layer i1 was depositedthereon by the so-called HRCVD method in which hydrogen gas wasactivated with microwave plasma and reacted with SiF₄ to deposit asemiconductor layer.

COMPARATIVE EXAMPLE 2

[0122] A photovoltaic element was produced in a similar manner to thatof Example 2 with the exception that the n-type semiconductor layer n1was not treated with a laser.

COMPARISON OF EXAMPLE 2 AND COMPARATIVE EXAMPLE 2

[0123] The photovoltaic element characteristics of these photovoltaicelements were measured in a similar manner to that of Example 1 andComparative Example 1. The results are shown in Table 6 in terms ofrelative values when the results of Comparative Example 2 are expressedas 1. The photovoltaic element of Example 2 showed superior photovoltaiccharacteristics in comparison to the Comparative Example 2 element.

[0124] Further, a cross section of each of these photovoltaic elementswas observed with an electron microscope and the amount of impuritieswas measured by secondary ion mass spectroscopy. As a result, it wasconfirmed for the photovoltaic element of Example 2 that a portion ofeach of the n-type semiconductor layer and the i-type semiconductorlayer were formed within the same microcrystal grains. The shape of themicrocrystal grains was columnar, the length in the layer thicknessdirection was 3000 Å, and the length in the direction perpendicular tothe layer thickness direction was 300 Å.

EXAMPLE 3

[0125] A photovoltaic element was produced in a similar manner to thatof Example 1 with the exception that in place of the method of Example 1in which the i-type semiconductor layer i1 was stacked on the n-typesemiconductor layer n1 crystallized by laser, a method was used in whichafter depositing the n-type semiconductor layer n1, a hydrogen plasmatreatment shown in Table 7 was performed in the i-type semiconductorlayer deposition chamber 202, and a source gas for formation of ani-type semiconductor layer was added without discontinuing the dischargeto deposit the i-type semiconductor layer i1.

COMPARISON OF EXAMPLE 3 AND COMPARATIVE EXAMPLE 1

[0126] The photovoltaic characteristics of the photovoltaic element ofExample 3 were evaluated in a similar manner to that of Example 1. Theresults are shown in Table 8 in terms of relative values when theresults of Comparative Example 1 are expressed as 1.

[0127] As is clear from Table 8, the photovoltaic element of Example 3showed superior photovoltaic characteristics.

EXAMPLE 4

[0128] Using the deposited film forming apparatus shown in FIG. 2, aphotovoltaic element was formed under the deposited film formationconditions shown in Table 9. After depositing a microcrystalline i-typesemiconductor layer (i0 layer), phosphorous atoms were implanted intothe i0 layer under the conditions shown in Table 10 with an ionimplantation apparatus not shown, followed by annealing to activate thephosphorous atoms.

COMPARISON OF EXAMPLE 4 AND COMPARATIVE EXAMPLE 1

[0129] The photovoltaic characteristics of the photovoltaic element ofExample 4 were evaluated in a similar manner to that of Example 1. Theresults are shown in Table 11 in terms of relative values when theresults of Comparative Example 1 are expressed as 1.

[0130] As is clear from Table 11, the photovoltaic element of Example 4showed superior photovoltaic characteristics.

[0131] When a cross section of the photovoltaic element of Example 4 wasobserved with an electron microscope, it was confirmed for the i0 layerthat uniform microcrystal grains were formed extending over the whole inthe layer thickness direction in a layer thickness of 3000 Å. It wasfurther confirmed through secondary ion mass spectroscopy that theimplanted phosphorous atoms were distributed only on the substrate side,namely that a semiconductor junction was formed within a singlemicrocrystal grain.

EXAMPLE 5

[0132] Using the deposited film forming apparatus shown in FIG. 2, aphotovoltaic element was formed under the deposited film formationconditions shown in Table 12. The microcrystalline semiconductor havinga semiconductor junction within the same microcrystal grain was usedbetween the n-type and the i-type semiconductor layers n1 and i1 of thebottom photovoltaic element. After deposition of the n-typesemiconductor layer n1, the n-type semiconductor layer n1 was irradiatedwith an excimer laser under the conditions shown in Table 2 in theloading chamber to crystallize the n-type semiconductor layer n1.Afterwards, an i-type semiconductor layer i1 was successively depositedon the n-type semiconductor layer n0 with the VHF plasma CVD method.

COMPARATIVE EXAMPLE 3

[0133] A photovoltaic element for comparison with Example 5 was producedin a similar manner to that of Example 5 with the exception that then-type semiconductor layer was not treated with an excimer laser.

COMPARISON OF EXAMPLE 5 AND COMPARATIVE EXAMPLE 3

[0134] The photovoltaic element characteristics of these photovoltaicelements were measured in a similar manner to that of Example 1 andComparative Example 1. These results are shown in Table 13 in terms ofrelative values when the results of Comparative Example 3 are expressedas 1. The photovoltaic element of Example 5 showed photovoltaiccharacteristics superior to the element of Comparative Example 3. Also,the photovoltaic element of the present invention had lower seriesresistance and larger shunt resistance in comparison with the element ofComparative Example 3.

[0135] One hundred photovoltaic elements each were then produced underthe same conditions as Example 5 and Comparative Example 3. Thesephotovoltaic elements were then left for 2000 hours in an atmosphere of85° C. temperature and 85% humidity. Afterwards their photovoltaiccharacteristics were measured. The 100 photovoltaic elements of Example5 had an extremely small variance of the characteristics as comparedwith the elements of Comparative Example 3. In other words, thephotovoltaic elements of the present invention have extremely highresistance to environment (durability).

[0136] When a cross section of each of these photovoltaic elements wasobserved with a transmission electron microscope, it was confirmed forthe photovoltaic elements of Example 5 that the region thought to be theboundary between the n-type semiconductor layer and the i-typesemiconductor layer was constituted of microcrystal grains 2000-5000 Ålong in the film thickness direction. It was also confirmed throughsecondary ion mass spectroscopy that the impurities (dopant) werelocalized on the substrate side of these microcrystal grains.

EXAMPLE 6

[0137] A photovoltaic element was produced in a similar manner to thatof Example 1 with the exception that after depositing the p-typesemiconductor layer, the p-type semiconductor layer was irradiated withan excimer laser under the same conditions of laser irradiation as thecrystallization of the n-type semiconductor layer, i.e., the conditionsshown in Table 2. Through this irradiation a microcrystalline layer wasformed having a semiconductor junction within the microcrystal grain,further between the i-type semiconductor layer and the p-typesemiconductor layer.

COMPARISON OF EXAMPLE 6 WITH EXAMPLE 1 AND COMPARATIVE EXAMPLE 1

[0138] The photovoltaic element of Example 6 was evaluated in a similarmanner to that of Example 1. These results are shown in Table 14 interms of relative values when the results of Comparative Example 1 areexpressed as 1. The photovoltaic element of Example 6 showed excellentcharacteristics in comparison with the element of Comparative Example 1and the element of Example 1.

[0139] A transmission electron microscope and a secondary ion massspectrometer were used to confirm whether or not a semiconductorjunction was formed within the same microcrystal grain in thephotovoltaic element of this example. As a result, it was confirmed thatthe element of this example had the n-type semiconductor layer and thei-type semiconductor layer within the same microcrystal grains and hadthe i-type semiconductor layer and the p-type semiconductor layer withinthe same microcrystal grains.

[0140] From the above, it was confirmed that the photovoltaic elementhaving the n-type semiconductor layer and the i-type semiconductor layerwithin the same microcrystal grains and having the i-type semiconductorlayer and the p-type semiconductor layer within the same microcrystalgrains has the best characteristics.

[0141] One hundred photovoltaic elements each of Example 6 andComparative Example 1 were then produced, and left for 3000 hours in anatmosphere of a nitrogen oxide at 85° C. temperature and 95% humiditywhile irradiating them with light of AM 1.5 and 100 mW/cm². Afterwardstheir photovoltaic characteristics were measured. The photovoltaicelements of Example 6 had less change in characteristics than theelements of Comparative Example 1.

[0142] Further, the current values when a 2V reverse bias was applied tothe photovoltaic elements of Example 6 and the elements of ComparativeExample 1 were compared. The results showed that the current values ofthe photovoltaic elements of Example 6 were approximately one orderlower than those for the elements of Comparative Example 1.

EXAMPLE 7

[0143] In this example a photovoltaic element was produced using thedeposited film forming apparatus shown in FIG. 2. The depositionconditions of each of the semiconductor layers are shown in Table 15.The formation of the members such as electrodes in all the examplesincluding this example and comparative examples was made following aconventional method. When depositing the bottom photovoltaic element,the input power was changed every 6 second period between the numericalvalue shown in Table 15 and a numerical value 1.5 times that. Themicrocrystalline semiconductor having a semiconductor junction withinthe same microcrystalline semiconductor of the present invention wasused between the n-type semiconductor layer n1 and an i-typesemiconductor layer i1 of the bottom photovoltaic element. Afterdeposition of the n-type semiconductor layer n1, the n-typesemiconductor layer n1 was irradiated with an excimer laser under theconditions shown in Table 16 in the loading chamber to crystalize then-type semiconductor layer n1. Afterwards, the i-type semiconductorlayer i1 was successively deposited on the n-type semiconductor layer n1by the VHF plasma CVD method.

COMPARATIVE EXAMPLE 4

[0144] A photovoltaic element for comparison with Example 7 was producedin a similar manner to that of Example 7 with the exception that theinput power was set at the constant value shown in Table 15 and that then-type semiconductor layer n1 was not treated with an excimer laser.

COMPARISON OF EXAMPLE 7 WITH COMPARATIVE EXAMPLE 4

[0145] The characteristics of the photovoltaic elements thus formed weremeasured and evaluated using WXS-130S-20T (trade name; mfd. by WACOMCO.) as a light source. The spectrum of the light source was AM 1.5 andthe light intensity was 1 sun. The results are shown in Table 17 interms of relative values when the results of Comparative Example 4 areexpressed as 1. The photovoltaic element of Example 7 showed excellentphotovoltaic characteristics as compared to the Comparative Example 4element. Further, as compared to the Comparative Example 4 element, thephotovoltaic element of Example 7 had a lower series resistance and alarger shunt resistance.

[0146] One hundred photovoltaic elements each were then produced underthe same conditions of Example 7 and Comparative Example 4. Thesephotovoltaic elements were left for 2000 hours in an atmospherecontaining acetic acid at 85° C. temperature and 85% humidity.Afterwards the photovoltaic characteristics were measured. Compared tothe elements of Comparative Example 4, the characteristics of the 100photovoltaic elements of Example 7 showed an extremely small variance.In other words, the photovoltaic elements of the present invention hadan extremely high resistance to environment (durability).

[0147] When a cross section of each of these photovoltaic elements wasobserved with a transmission electron microscope, it was confirmed forthe photovoltaic elements of Example 7 that the region thought to be theboundary between the n-type semiconductor layer and the i-typesemiconductor layer was constituted of microcrystal grains with a lengthin the layer thickness direction of 2000 to 4000 Å. Further, throughsecondary ion mass spectroscopy, it was confirmed that the impurities(dopant) were localized on the substrate side of the microcrystalgrains.

[0148] Further, it was confirmed through the dark-field image of anelectron microscope that microcrystal grains with different sizes weredistributed within the semiconductor layers of the bottom photovoltaicelement of Example 7. On the other hand it was also confirmed thatmicrocrystal grains of a uniform size were distributed in thesemiconductor layers of the bottom photovoltaic element of ComparativeExample 4.

EXAMPLE 8

[0149] A photovoltaic element was produced under the deposited filmformation conditions shown in Table 18 using the deposited film formingapparatus of FIG. 2 in the same manner as in Example 7. The n-typesemiconductor layer n1 was irradiated with an excimer laser under theconditions shown in Table 19 to be crystallized in a similar manner tothat of Example 7. A bottom i-type semiconductor layer i1 was depositedthereon by the so-called HRCVD method in which hydrogen gas wasactivated with microwave plasma and reacted with SiF₄ to deposit asemiconductor layer. When depositing the bottom i-type semiconductorlayer i1, the microwave energy was changed every 6 seconds between thevalue shown in Table 18 and a value of 1.3 times the value of Table 18.

COMPARATIVE EXAMPLE 5

[0150] A photovoltaic element for comparison with Example 8 was producedin a similar manner to that of Example 8 with the exception that themicrowave power during deposition of the i-type semiconductor layer i1was set at the constant value shown in Table 18 and that the n-typesemiconductor layer n1 was not treated with an excimer laser.

COMPARISON OF EXAMPLE 8 AND COMPARATIVE EXAMPLE 5

[0151] The photovoltaic element characteristics of these photovoltaicelements were measured in a similar manner to that of Example 7 andComparative Example 4. The results are shown in Table 20 in terms ofrelative values when the results of Comparative Example 5 are expressedas 1. The photovoltaic element of Example 8 showed superior photovoltaiccharacteristics in comparison to the Comparative Example 5 element.

[0152] Further, a cross section of each of these photovoltaic elementswas observed with an electron microscope and the amount of impuritieswas measured by secondary ion mass spectroscopy. As a result, it wasconfirmed for the photovoltaic element of Example 8 that a portion ofeach of the n-type semiconductor layer and the i-type semiconductorlayer were formed within the same microcrystal grains. The shape of themicrocrystal grains was columnar, the length in the layer thicknessdirection was 3000 Å, and the length in the direction perpendicular tothe layer thickness direction was 300 Å.

[0153] Further, when the dark field image of these photovoltaic elementswas observed with a transmission electron microscope, spaces unfilled bymicrocrystal grains in the photovoltaic elements of Comparative Example5 were observed, but in Example 8 the spaces were filled bymicrocrystals with different grain diameters.

EXAMPLE 9

[0154] A photovoltaic element was produced in a similar manner to thatof Example 7 with the exception that in place of the method of Example 7in which the i-type semiconductor layer i1 was stacked on the n-typesemiconductor layer n1 crystallized by laser, a method was used in whichafter depositing the n-type semiconductor layer n1, a hydrogen plasmatreatment shown in Table 21 was performed in the i-type semiconductorlayer deposition chamber 202, and a source gas for formation of ani-type semiconductor layer was added without discontinuing the dischargeto deposit the i-type semiconductor layer i1.

COMPARISON OF EXAMPLE 9 AND COMPARATIVE EXAMPLE 4

[0155] The photovoltaic characteristics of the photovoltaic element ofExample 9 were evaluated in a similar manner to that of Example 7. Theresults are shown in Table 22 in terms of relative values when theresults of Comparative Example 4 are expressed as 1.

[0156] As is clear from Table 22, the photovoltaic element of Example 9showed superior photovoltaic characteristics.

EXAMPLE 10

[0157] Using the deposited film forming apparatus shown in FIG. 2, aphotovoltaic element was formed under the deposited film formationconditions shown in Table 23. After depositing a microcrystalline i-typesemiconductor layer (i0 layer), phosphorous atoms were implanted intothe i0 layer under the conditions shown in Table 24 with an ionimplantation apparatus not shown, followed by annealing to activate thephosphorous atoms. When depositing the layer i, SiF₄ gas of 50% of thesilane gas was added at a rate of 10 times per minute for one second peraddition.

COMPARISON OF EXAMPLE 10 AND COMPARATIVE EXAMPLE 4

[0158] The photovoltaic characteristics of the photovoltaic element ofExample 10 were evaluated in a similar manner to that of Example 7. Theresults are shown in Table 25 in terms of relative values when theresults of Comparative Example 4 are expressed as 1.

[0159] As is clear from Table 25, the photovoltaic element of Example 10showed superior photovoltaic characteristics.

[0160] When a cross section of the photovoltaic element of Example 10was observed with an electron microscope, it was confirmed for the i0layer that uniform microcrystal grains were formed extending over thewhole in the layer thickness direction in a layer thickness of 3000 Å.It was further confirmed through secondary ion mass spectroscopy thatthe implanted phosphorous atoms were distributed only on the substrateside, namely that a semiconductor junction was formed within a singlemicrocrystal grain.

[0161] Further, the dark field image of a transmission electronmicroscope was observed and X-ray diffraction was measured. When theaverage crystal grain diameter in the photovoltaic element ofComparative Example 4 was calculated from the half-width of the X-raydiffraction (220) peaks, it was approximately 200 Å. When the averagecrystal grain diameter in the photovoltaic element of ComparativeExample 4 was calculated from the dark field image of the transmissionelectron microscope, it was approximately 200 Å. On the other hand, whenthe average crystal grain diameter in the photovoltaic element ofExample 10 was calculated from the half-width of the X-ray diffraction(220) peaks, it was approximately 250 Å. When the average crystal graindiameter in the photovoltaic element of Example 10 was calculated fromthe dark field image of the transmission electron microscope, it wasapproximately 750 Å. The difference in the average diameter calculatedfrom X-ray diffraction and the average diameter calculated bytransmission electron microscope shows that microcrystals with differentgrain diameters exist within the microcrystalline semiconductor layer ofExample 10.

EXAMPLE 11

[0162] Using the deposited film forming apparatus shown in FIG. 2, aphotovoltaic element was formed under the deposited film formationconditions shown in Table 26. The microcrystalline semiconductor havinga semiconductor junction within the same microcrystal grain was usedbetween the n-type and the i-type semiconductor layers n1 and i1 of thebottom photovoltaic element. After deposition of the n-typesemiconductor layer n1, the n-type semiconductor layer nl was irradiatedwith an excimer laser under the conditions shown in Table 16 in theloading chamber to crystallize the n-type semiconductor layer n1.Afterwards, an i-type semiconductor layer i1 was successively depositedon the n-type semiconductor layer n0 with the VHF plasma CVD method.When depositing the i-type semiconductor layer i1, the input power ofVHF was changed every 3 seconds between the value shown in Table 26 anda value of 1.3 times the value of Table 18.

COMPARATIVE EXAMPLE 6

[0163] A photovoltaic element for comparison with Example 11 wasproduced in a similar manner to that of Example 11 with the exceptionthat the n-type semiconductor layer was not treated with an excimerlaser and that the VHF power was set at the constant value shown inTable 26.

COMPARISON OF EXAMPLE 11 AND COMPARATIVE EXAMPLE 6

[0164] The photovoltaic element characteristics of these photovoltaicelements were measured in a similar manner to that of Example 7 andComparative Example 4. These results are shown in Table 27 in terms ofrelative values when the results of Comparative Example 6 are expressedas 1. The photovoltaic element of Example 11 showed photovoltaiccharacteristics superior to the element of Comparative Example 6. Also,the photovoltaic element of Example 11 had lower series resistance andlarger shunt resistance in comparison with the element of ComparativeExample 6.

[0165] One hundred photovoltaic elements each were then produced underthe same conditions as Example 11 and Comparative Example 6. Thesephotovoltaic elements were then left for 2000 hours in an atmosphere of85° C. temperature and 85% humidity. Afterwards their photovoltaiccharacteristics were measured. The 100 photovoltaic elements of Example11 had an extremely small variance of the characteristics as comparedwith the elements of Comparative Example 6. In other words, thephotovoltaic elements of the present invention have extremely highresistance to environment (durability).

[0166] When a cross section of each of these photovoltaic elements wasobserved with a transmission electron microscope, it was confirmed forthe photovoltaic elements of Example 11 that the region thought to bethe boundary between the n-type semiconductor layer and the i-typesemiconductor layer was constituted of microcrystal grains 2000-5000 Ålong in the film thickness direction. It was also confirmed throughsecondary ion mass spectroscopy that the impurities (dopant) werelocalized on the substrate side of these microcrystal grains.

EXAMPLE 12

[0167] A photovoltaic element was produced in a similar manner to thatof Example 7 with the exception that after depositing the p-typesemiconductor layer, the p-type semiconductor layer was irradiated withan excimer laser under the same conditions of laser irradiation as thecrystallization of the n-type semiconductor layer, i.e., the conditionsshown in Table 16. Through this irradiation a microcrystalline layer wasformed having a semiconductor junction within the microcrystal grain,further between the i-type semiconductor layer and the p-typesemiconductor layer.

COMPARISON OF EXAMPLE 12 WITH EXAMPLE 7 AND COMPARATIVE EXAMPLE 4

[0168] The photovoltaic element of Example 12 was evaluated in a similarmanner to that of Example 7. These results are shown in Table 28 interms of relative values when the results of Comparative Example 4 areexpressed as 1. The photovoltaic element of Example 12 showed excellentcharacteristics in comparison with the element of Comparative Example 4and the element of Example 7.

[0169] A transmission electron microscope and a secondary ion massspectrometer were used to confirm whether or not a semiconductorjunction was formed within the same microcrystal grain in thephotovoltaic element of this example. As a result, it was confirmed thatthe element of this example had the n-type semiconductor layer and thei-type semiconductor layer within the same microcrystal grains and hadthe i-type semiconductor layer and the p-type semiconductor layer withinthe same microcrystal grains.

[0170] From the above, it was confirmed that the photovoltaic elementhaving the n-type semiconductor layer and the i-type semiconductor layerwithin the same microcrystal grains and having the i-type semiconductorlayer and the p-type semiconductor layer within the same microcrystalgrains has the best characteristics.

[0171] One hundred photovoltaic elements each of Example 12 andComparative Example 4 were then produced, and left for 3000 hours in anatmosphere of a nitrogen oxide at 85° C. temperature and 95% humiditywhile irradiating them with light of AM 1.5 and 100 mW/cm². Afterwardstheir photovoltaic characteristics were measured. The photovoltaicelements of Example 12 had less change in characteristics than theelements of Comparative Example 1.

[0172] Further, the current values when a 2V reverse bias was applied tothe photovoltaic elements of Example 12 and the elements of ComparativeExample 4 were compared. The results showed that the current values ofthe photovoltaic elements of Example 12 were approximately one orderlower than those for the elements of Comparative Example 4.

[0173] As mentioned above, the defect states in the vicinity of theinterfaces can be greatly reduced by forming semiconductor junctionssuch as p/i or n/i within the same microcrystal grains. As a result itis possible to prevent a decline in the open circuit voltage (Voc),short circuit current (Jsc), and fill factor (FF) of the photovoltaicelement. Further, it is possible to prevent an increase in the seriesresistance and a decline in the shunt resistance of the photovoltaicelement. As a result the photoelectric conversion efficiency of thephotovoltaic device is improved.

[0174] The heat resistant properties of the semiconductor element alsoimproves due to the formation of a semiconductor junction within themicrocrystal grains.

[0175] In addition, it is possible to prevent degradation incharacteristics caused by air or an encapsulant by forming asemiconductor junction within the microcrystal grains.

[0176] Further, a depletion layer of a semiconductor junction spreadsfurther than in semiconductor elements having conventional semiconductorjunctions, by forming a semiconductor junction within microcrystalgrains. As a result the rectifying characteristics are better than inconventional semiconductor junctions and the dark current is kept lowerwhen a reverse bias is applied.

[0177] Further, by presence of microcrystal grains with different graindiameters, it is possible to make the distortion smaller than whenfilling three dimensional spaces (the semiconductor layer) withmicrocrystal grains with a uniform grain diameter. As a result, thetransportability (mobility) of the photo-excited free carriers withinthe microcrystalline semiconductor layer increases and the life time ofthe carriers is extended. TABLE 1 Sub- Power Deposi- strate Layer GasDensity Vacuum tion Tempera- Thick- PH₃ BF₃ (W/cm³) Degree Rate tureness SiH₄ H₂ (2%/H₂) (2%/H₂) RF VHF (mTorr) (Å/s) (° C.) (Å) Bottom n1 248 0.5 0.0382 1300 1 225 200 i1 25 750  0.12  300 1 250 15000  p1 0.02535 1 1.15  2000 1 165  50 Top n2 2 48 0.5 0.0382 1300 1 225 100 i2 2 480.0382 1150 1 200 3000  p2 0.025 35 1 1.15  2000 1 165  50

[0178] TABLE 2 Wave Length Output Vacuum Degree Excimer Laser nm mJ/cm²Torr XeCl 308 500 1E−05

[0179] TABLE 3 Open Short Circuit Circuit Conversion Voltage CurrentFill Factor Efficiency Comparative 1 1 1 1 Example 1 Example 1 1.02 11.03 1.05

[0180] TABLE 4 Sub- Power Deposi- strate Layer Gas Density Vacuum tionTempera- Thick- PH₃ BF₃ (W/cm³) Degree Rate ture ness SiH₄ SiF₄ H₂(2%/H₂) (2%/H₂) RF VHF MW (mTorr) (Å/s) (° C.) (Å) Bottom n1 2 48 0.50.0382 1300 1 225 200 i1 100 300  0.6  250 20 250 20000  p1 0.025 35 11.15  2000 1 165  50 Top n2 2 48 0.5 0.0382 1300 1 225 100 i2 2 480.0382 1150 1 200 3500  p2 0.025 35 1 1.15  2000 1 165  50

[0181] TABLE 5 Wave Length Output Vacuum Degree Excimer Laser nm mJ/cm²Torr XeCl 308 600 1E−05

[0182] TABLE 6 Open Short Circuit Circuit Conversion Voltage CurrentFill Factor Efficiency Comparative 1 1 1 1 Example 2 Example 2 1.02 11.02 1.04

[0183] TABLE 7 Hydrogen Flow Substrate Rate Current Density VacuumDegree Temperature (sccm) (W/cm³) (Torr) (° C.) 100 0.1 0.5 300

[0184] TABLE 8 Open Short Circuit Circuit Conversion Voltage CurrentFill Factor Efficiency Comparative 1 1 1 1 Example 1 Example 3 1.02 1.011.02 1.05

[0185] TABLE 9 Sub- Power Deposi- strate Layer Gas Density Vacuum tionTempera- Thick- PH₃ BF₃ (W/cm³) Degree Rate ture ness SiH₄ H₂ (2%/H₂)(2%/H₂) RF VHF (mTorr) (Å/s) (° C.) (Å) Bottom i0 25 750  0.12  300 1250 3000 i1 25 750  0.12  300 1 250 14000  p1 0.025 35 1 1.15  2000 1165  50 Top n2 2 48 0.5 0.0382 1300 1 225  100 i2 2 48 0.0382 1150 1 2003000 p2 0.025 35 1 1.15  2000 1 165  50

[0186] TABLE 10 Substrate Annealing Addition Amount Vacuum DegreeTemperature Temperature (1/cm³) (Torr) (° C.) (° C.) 1E+20 1E−07 300 600

[0187] TABLE 11 Open Short Circuit Circuit Conversion Voltage CurrentFill Factor Efficiency Comparative 1 1 1 1 Example 1 Example 3 1.02 1.011.03 1.06

[0188] TABLE 12 Sub- Power Deposi- strate Layer Gas Density Vacuum tionTempera- Thick- PH₃ BF₃ (W/cm³) Degree Rate ture ness SiH₄ GeH₄ H₂(2%/H₂) (2%/H₂) RF VHF (mTorr) (Å/s) (° C.) (Å) Bottom ni 1  1 48 0.50.0382 1300 1 225  200 i1 12 12 750  0.12  300 1 250 10000  p1 0.025 351 1.15  2000 1 165  50 Top n2 2 48 0.5 0.0382 1300 1 225  100 i2 2 480.0382 1150 1 200 3500 p2 0.025 35 1 1.15  2000 1 165  50

[0189] TABLE 13 Open Short Circuit Circuit Conversion Voltage CurrentFill Factor Efficiency Comparative 1 1 1 1 Example 3 Example 5 1.01 1.011.01 1.03

[0190] TABLE 14 Open Short Circuit Circuit Conversion Voltage CurrentFill Factor Efficiency Comparative 1 1 1 1 Example 1 Example 1 1.02 11.03 1.05 Example 6 1.03 1.01 1.04 1.08

[0191] TABLE 15 Sub- Power Deposi- strate Layer Gas Density Vacuum tionTempera- Thick- PH₃ BF₃ (W/cm³) Degree Rate ture ness SiH₄ H₂ (2%/H₂)(2%/H₂) RF VHF (mTorr) (Å/s) (° C.) (Å) Bottom n1 2 48 0.5 0.0382 1300 1225 200 i1 25 750  0.15  300 1 300 15500  p1 0.025 35 1 1.15  2000 1 165 50 Top n2 2 48 0.5 0.0382 1130 1 225 100 i2 2 48 0.0382 1150 1 2003000  p2 0.025 35 1 1.15  2000 1 165  50

[0192] TABLE 16 Wave Length Output Vacuum Degree Excimer Laser mn mJ/cm²Torr XeCl 308 500 1E − 05

[0193] TABLE 17 Open Short Circuit Circuit Conversion Voltage CurrentFill Factor Efficiency Comparative 1 1 1 1 Example 4 Example 7 1.0211.001 1.032 1.055

[0194] TABLE 18 Sub- Power Deposi- strate Layer Gas Density Vacuum tionTempera- Thick- PH₃ BF₃ (W/cm³) Degree Rate ture ness SiH₄ SiF₄ H₂(2%/H₂) (2%/H₂) RF MW (mTorr) (Å/s) (° C.) (Å) Bottom n1 2 48 0.5 0.03821300 1 225  200 i1 100 350  0.62  250 20  250 20000  p1 0.025 35 1 1.15 2000 1 165  50 Top n2 2 48 0.5 0.0382 1300 1 225  100 i2 2 48 0.03821150 1 200 3500 p2 0.025 35 1 1.15  2000 1 165  50

[0195] TABLE 19 Wave Length Output Vacuum Degree Excimer Laser nm mJ/cm²Torr XeCl 308 600 1E − 05

[0196] TABLE 20 Open Short Circuit Circuit Conversion Voltage CurrentFill Factor Efficiency Comparative 1 1 1 1 Example 5 Example 8 1.0321.01 1.022 1.065

[0197] TABLE 21 Hydrogen Flow Substrate Rate Current Density VacuumDegree Temperature (sccm) (W/cm³) Torr (° C.) 100 0.1 0.5 300

[0198] TABLE 22 Open Short Circuit Circuit Conversion Voltage CurrentFill Factor Efficiency Comparative 1 1 1 1 Example 4 Example 9 1.03 1.021.02 1.07

[0199] TABLE 23 Sub- Power Deposi- strate Layer Gas Density Vacuum tionTempera- Thick- PH₃ BF₃ (W/cm³) Degree Rate ture ness SiH₄ H₂ (2%/H₂)(2%/H₂) RF VHF (mTorr) (Å/s) (° C.) (Å) Bottom 0 25 750  0.12  300 1 2503000 i1 25 750  0.12  300 1 350 16000  p1 0.025 35 1 1.15  2000 1 165 50 Top n2 2 48 0.5 0.0382 1300 1 225  100 i2 2 48 0.0382 1150 1 2003000 p2 0.025 35 1 1.15  2000 1 165  50

[0200] TABLE 24 Substrate Annealing Addition Amount Vacuum DegreeTemperature Temperature (1/cm³) (Torr) (° C.) (° C.) 1E + 20 1E − 07 300600

[0201] TABLE 25 Open Short Circuit Circuit Conversion Voltage currentFill Factor Efficiency Comparative 1 1 1 1 Example 4 Example 10 1.031.01 103 1.07

[0202] TABLE 26 Sub- Power Deposi- strate Layer Gas Density Vacuum tionTempera- Thick- PH₃ BF₃ (W/cm³) Degree Rate ture ness SiH₄ GeH₄ H₂(2%/H₂) (2%/H₂) RF VHF (mTorr) (Å/s) (° C.) (Å) Bottom ni 1  1 48 0.50.0382 1300 1 225 200 i1 12 12 800  0.17  200 1 300 10000  p1 0.025 35 11.15  2000 1 165  50 Top n2 2 48 0.5 0.0382 1300 1 225 100 i2 2 480.0382 1150 1 200 3000  p2 0.025 35 1 1.15  2000 1 165  50

[0203] TABLE 27 Open Short Circuit Circuit Conversion Voltage CurrentFill Factor Efficiency Comparative 1 1 1 1 Example 6 Example 11 1.0121.03 1.03 1.074

[0204] TABLE 28 Open Short Circuit Circuit Conversion Voltage CurrentFill Factor Efficiency Comparative 1 1 1 1 Example 4 Example 4 1.0211.001 1.032 1.055 Example 12 1.032 1.02 1.04 1.095

What is claimed is:
 1. A semiconductor element comprisingmicrocrystalline semiconductor, having a semiconductor junction in amicrocrystal grain.
 2. The semiconductor element according to claim 1 ,wherein the microcrystalline semiconductor comprises silicon atoms. 3.The semiconductor element according to claim 1 , wherein themicrocrystalline semiconductor comprises germanium atoms.
 4. Thesemiconductor element according to claim 1 , wherein themicrocrystalline semiconductor comprises hydrogen atoms.
 5. Thesemiconductor element according to claim 1 , wherein themicrocrystalline semiconductor comprises halogen atoms.
 6. Thesemiconductor element according to claim 1 , wherein the microcrystalgrain is columnar.
 7. A semiconductor element comprising a semiconductorlayer having first electric characteristics, a semiconductor layerhaving second electric characteristics, and a semiconductor layer havingthird electric characteristics stacked in the named order, wherein amicrocrystal grain is present extending over at least a portion of thesemiconductor layer having the first electric characteristics and atleast a portion of the semiconductor layer having the second electriccharacteristics.
 8. The semiconductor element according to claim 7 ,wherein a microcrystal grain is present extending over at least aportion of the semiconductor layer having the second electriccharacteristics and at least a portion of the semiconductor layer havingthe third electric characteristics.
 9. The semiconductor elementaccording to claim 7 , wherein one of the semiconductor layer having thefirst electric characteristics and the semiconductor layer having thethird electric characteristics is a p-type semiconductor layer and theother thereof is an n-type semiconductor layer, and wherein thesemiconductor layer having the second electric characteristics is ani-type semiconductor layer.
 10. A semiconductor element comprisingmicrocrystalline semiconductor, having a region where microcrystalgrains with different grain diameters are present as a mixture.
 11. Thesemiconductor element according to claim 10 , wherein themicrocrystalline semiconductor comprises silicon atoms.
 12. Thesemiconductor element according to claim 10 , wherein themicrocrystalline semiconductor comprises germanium atoms.
 13. Thesemiconductor element according to claim 10 , wherein themicrocrystalline semiconductor comprises hydrogen atoms.
 14. Thesemiconductor element according to claim 10 , wherein themicrocrystalline semiconductor comprises halogen atoms.
 15. Thesemiconductor element according to claim 10 , wherein the microcrystalgrains are columnar.
 16. The semiconductor element according to claim 10, having a semiconductor junction in the microcrystal grains.
 17. Asemiconductor element comprising a semiconductor layer having firstelectric characteristics, a semiconductor layer having second electriccharacteristics and a semiconductor layer having third electriccharacteristics stacked in the named order, wherein microcrystal grainswith different grain diameters are present as a mixture in at least oneof the semiconductor layers.
 18. The semiconductor element according toclaim 17 , wherein a microcrystal grain is present extending over atleast a portion of the semiconductor layer having the first electriccharacteristics and at least a portion of the semiconductor layer havingthe second electric characteristics.
 19. The semiconductor elementaccording to claim 17 , wherein one of the semiconductor layer havingthe first electric characteristics and the semiconductor layer havingthe third electric characteristics is a p-type semiconductor layer andthe other thereof is an n-type semiconductor layer, and wherein thesemiconductor layer having the second electric characteristics is ani-type semiconductor layer.
 20. A method of manufacturing asemiconductor element, comprising the steps of: forming a semiconductorlayer having first electric characteristics on a substrate;crystallizing the semiconductor layer having the first electriccharacteristics; and growing a crystalline semiconductor layer havingsecond electric characteristics on the crystallized semiconductor layerhaving the first electric characteristics, thereby growing amicrocrystal grain so as to extend over the semiconductor layer havingthe first electric characteristics and the semiconductor layer havingthe second electric characteristics.
 21. A method of manufacturing asemiconductor element, comprising the steps of: forming a crystallinesemiconductor layer having first electric characteristics on asubstrate; and growing a crystalline semiconductor layer having secondelectric characteristics on the semiconductor layer having the firstelectric characteristics, thereby growing a microcrystal grain so as toextend over the semiconductor layer having the first electriccharacteristics and the semiconductor layer having the second electriccharacteristics.
 22. A method of manufacturing a semiconductor element,comprising the steps of: forming a semiconductor layer having firstelectric characteristics on a substrate; growing a semiconductor layerhaving second electric characteristics on the semiconductor layer havingthe first electric characteristics; and effecting annealing to form amicrocrystal grain so as to extend over the semiconductor layer havingthe first electric characteristics and the semiconductor layer havingthe second electric characteristics.
 23. A method of manufacturing asemiconductor element, comprising the steps of: forming a crystallinesemiconductor layer on a substrate; and ion-implanting a dopant into thesemiconductor layer to form a semiconductor junction in a microcrystalgrain of the semiconductor layer.
 24. A method of manufacturing asemiconductor element, comprising the step of generating a plasma in agas phase to decompose a source gas thus forming a semiconductor layercomprising microcrystals on a substrate, wherein an electric power to beapplied to the plasma is periodically changed to form a semiconductorlayer comprising microcrystal grains of different sizes as a mixture.25. A method of manufacturing a semiconductor element, comprising thestep of generating a plasma in a gas phase to decompose a source gasthus forming a semiconductor layer comprising microcrystals on asubstrate, wherein a halogen-containing gas is added at regularintervals into the source gas to form a semiconductor layer comprisingmicrocrystal grains of different sizes as a mixture.